Question 1

The first step of the proton-proton cycle is:

Accepted Answer

A) "1H + 1H $\rightarrow$ 2H" 
B) "1H + 1H $\rightarrow$ 2H + e+ +  v " 
C) "1H + 1H $\rightarrow$ 2H + e- +  v " 
D) "1H + 1H $\rightarrow$ 2H +  1v " 
E) "1H + 1H  v 3H + e- +  v " 
A) "1H + 1H $\rightarrow$ 2H" 
B) "1H + 1H $\rightarrow$ 2H + e+ +  v " 
C) "1H + 1H $\rightarrow$ 2H + e- +  v " 
D) "1H + 1H $\rightarrow$ 2H +  1v " 
E) "1H + 1H  v 3H + e- +  v "

Question 2

Separation of the isotopes of uranium requires a physical, rather than chemical, method because:

Accepted Answer

A) mixing other chemicals with uranium is too dangerous 
B) the isotopes are chemically the same 
C) the isotopes have exactly the same number of neutrons per nucleus 
D) natural uranium contains only 0.7% 235U 
E) uranium is the heaviest element in nature 
A) mixing other chemicals with uranium is too dangerous 
B) the isotopes are chemically the same 
C) the isotopes have exactly the same number of neutrons per nucleus 
D) natural uranium contains only 0.7% 235U 
E) uranium is the heaviest element in nature

Question 3

In the uranium disintegration series:

Accepted Answer

A) the emission of a  $\beta$ - particle increases the mass number A by one and decreases the atomic number Z by one 
B) the disintegrating element merely ejects atomic electrons 
C) the emission of an  $\alpha$  particle decreases the mass number A by four and decreases the atomic number Z by two 
D) the nucleus always remains unaffected 
E) the series of disintegrations continues until an element having eight outermost orbital electrons is obtained 
A) the emission of a  $\beta$ - particle increases the mass number A by one and decreases the atomic number Z by one 
B) the disintegrating element merely ejects atomic electrons 
C) the emission of an  $\alpha$  particle decreases the mass number A by four and decreases the atomic number Z by two 
D) the nucleus always remains unaffected 
E) the series of disintegrations continues until an element having eight outermost orbital electrons is obtained

Question 4

Tokamaks confine deuteron plasmas using:

Accepted Answer

A) thick steel walls 
B) magnetic fields 
C) laser beams 
D) vacuum tubes 
E) electric fields 
A) thick steel walls 
B) magnetic fields 
C) laser beams 
D) vacuum tubes 
E) electric fields

Question 5

Consider all possible fission events.Which of the following statements is true?

Accepted Answer

A) Light initial fragments have more protons than neutrons and heavy initial fragments have fewer protons than neutrons 
B) Heavy initial fragments have more protons than neutrons and light initial fragments have fewer protons than neutrons 
C) All initial fragments have more protons than neutrons 
D) All initial fragments have about the same number of protons and neutrons 
E) All initial fragments have more neutrons than protons 
A) Light initial fragments have more protons than neutrons and heavy initial fragments have fewer protons than neutrons 
B) Heavy initial fragments have more protons than neutrons and light initial fragments have fewer protons than neutrons 
C) All initial fragments have more protons than neutrons 
D) All initial fragments have about the same number of protons and neutrons 
E) All initial fragments have more neutrons than protons

Question 6

The energy released in a complete proton-proton cycle is about:

Accepted Answer

A) 3 keV 
B) 30 keV 
C) 3 MeV 
D) 30 MeV 
E) 300 MeV 
A) 3 keV 
B) 30 keV 
C) 3 MeV 
D) 30 MeV 
E) 300 MeV

Question 7

The overall proton-proton cycle is equivalent to:

Accepted Answer

A) 21H $\rightarrow$2H 
B) 41H $\rightarrow$4H 
C) 41H $\rightarrow$4H +4n 
D) 41H + 2e- $\rightarrow$ 4He + 2 v  + 6 $\gamma$ 
E) 41H + 2e+ $\rightarrow$ 4He + 2 v 
A) 21H $\rightarrow$2H 
B) 41H $\rightarrow$4H 
C) 41H $\rightarrow$4H +4n 
D) 41H + 2e- $\rightarrow$ 4He + 2 v  + 6 $\gamma$ 
E) 41H + 2e+ $\rightarrow$ 4He + 2 v

Question 8

Nuclear fusion in stars produces all the chemical elements with mass numbers less than:

Accepted Answer

A) 56 
B) 66 
C) 70 
D) 82 
E) 92 
A) 56 
B) 66 
C) 70 
D) 82 
E) 92

Question 9

Which one of the following represents a fission reaction that can be activated by slow neutrons?

Accepted Answer

A) "238U92 + 1n0 $\rightarrow$90Kr36 + 146Cs55 + 2H1 + 1n0" 
B) "239Pu94 + 1n0 $\rightarrow$96Sr38 + 141Ba56 + 31n0" 
C) "238U92 $\rightarrow$234Th90 + 4He2" 
D) "3H1 + 2H1 $\rightarrow$4He2 + 1n0" 
E) "107Ag47 + 1n0 $\rightarrow$108Ag47 $\rightarrow$108Cd48 + 0e-1" 
A) "238U92 + 1n0 $\rightarrow$90Kr36 + 146Cs55 + 2H1 + 1n0" 
B) "239Pu94 + 1n0 $\rightarrow$96Sr38 + 141Ba56 + 31n0" 
C) "238U92 $\rightarrow$234Th90 + 4He2" 
D) "3H1 + 2H1 $\rightarrow$4He2 + 1n0" 
E) "107Ag47 + 1n0 $\rightarrow$108Ag47 $\rightarrow$108Cd48 + 0e-1"

Question 10

Two billion years ago, a natural nuclear reactor formed in a uranium deposit in Africa.Why is it not possible for such a natural reactor to form somewhere on Earth today?

Accepted Answer

A) It is in fact possible for this to occur. 
B) Too much uranium has already been mined for this to occur. 
C) Too much 235U has now decayed for a critical mass to form naturally. 
D) The remaining uranium deposits are too far underground for this to occur. 
E) Uranium in the remaining deposits is mixed with too many other elements for this to occur. 
A) It is in fact possible for this to occur. 
B) Too much uranium has already been mined for this to occur. 
C) Too much 235U has now decayed for a critical mass to form naturally. 
D) The remaining uranium deposits are too far underground for this to occur. 
E) Uranium in the remaining deposits is mixed with too many other elements for this to occur.

Question 11

Lawson's number is 1020 s.m-3.If the density of deuteron nuclei is 2 * 1021 m-3 what should the confinement time be to achieve sustained fusion?

Accepted Answer

A) 16 ms 
B) 50 ms 
C) 160 ms 
D) 250 ms 
E) 20 s 
A) 16 ms 
B) 50 ms 
C) 160 ms 
D) 250 ms 
E) 20 s

Question 12

For purposes of a practical (energy producing)reaction one wants a disintegration energy Q that is:

Accepted Answer

A) positive for fusion reactions and negative for fission reactions 
B) negative for fusion reactions and positive for fission reactions 
C) negative for both fusion and fission reactions 
D) positive for both fusion and fission reactions 
E) as close to zero as possible for both fusion and fission reactions 
A) positive for fusion reactions and negative for fission reactions 
B) negative for fusion reactions and positive for fission reactions 
C) negative for both fusion and fission reactions 
D) positive for both fusion and fission reactions 
E) as close to zero as possible for both fusion and fission reactions

Question 13

In a subcritical nuclear reactor:

Accepted Answer

A) the number of fission events per unit time decreases with time 
B) the number of fission events per unit time increases with time 
C) each fusion event produces fewer neutrons than when the reactor is critical 
D) each fusion event produces more neutrons than when the reactor is critical 
E) none of the above 
A) the number of fission events per unit time decreases with time 
B) the number of fission events per unit time increases with time 
C) each fusion event produces fewer neutrons than when the reactor is critical 
D) each fusion event produces more neutrons than when the reactor is critical 
E) none of the above

Question 14

The energy supplied by a thermal neutron in a fission event is essentially its:

Accepted Answer

A) excitation energy 
B) binding energy 
C) kinetic energy 
D) rest energy 
E) electric potential energy 
A) excitation energy 
B) binding energy 
C) kinetic energy 
D) rest energy 
E) electric potential energy

Question 15

A nuclear reactor is operating at a certain power level, with its multiplication factor adjusted to unity.The control rods are now used to reduce the power output to one-half its former value.After the reduction in power the multiplication factor is maintained at:

Accepted Answer

A) 1/4 
B) 1/2 
C) 1 
D) 2 
E) 4 
A) 1/4 
B) 1/2 
C) 1 
D) 2 
E) 4

Question 16

The table lists properties of several heavy nuclei when they are struck by thermal neutrons; En is the excitation energy and Eb is the energy barrier.Which quantity, or combination of quantities, represents the energy put into the oscillation of the resulting compound nucleus?

Accepted Answer

A) En 
B) Eb 
C) En - Eb 
D) Eb - En 
E) Mass of the target nuclide + Eb 
A) En 
B) Eb 
C) En - Eb 
D) Eb - En 
E) Mass of the target nuclide + Eb

Question 17

Most of the energy produced by the Sun is due to:

Accepted Answer

A) nuclear fission 
B) nuclear fusion 
C) chemical reaction 
D) gravitational collapse 
E) induced emfs associated with the Sun's magnetic field 
A) nuclear fission 
B) nuclear fusion 
C) chemical reaction 
D) gravitational collapse 
E) induced emfs associated with the Sun's magnetic field

Question 18

235U is readily made fissionable by a thermal neutron but 238U is not because:

Accepted Answer

A) the neutron has a smaller binding energy in 236U 
B) the neutron has a smaller excitation energy in 236U 
C) the potential barrier for the fragments is less in 239U 
D) the neutron binding energy is greater than the barrier height for 236U and less than the barrier height for 239U 
E) the neutron binding energy is less than the barrier height for 236U and greater than the barrier height for 239U 
A) the neutron has a smaller binding energy in 236U 
B) the neutron has a smaller excitation energy in 236U 
C) the potential barrier for the fragments is less in 239U 
D) the neutron binding energy is greater than the barrier height for 236U and less than the barrier height for 239U 
E) the neutron binding energy is less than the barrier height for 236U and greater than the barrier height for 239U

Question 19

When 236U fissions the fragments are:

Accepted Answer

A) always 140Xe and 94Sr 
B) always identical 
C) never 140Xe and 94Sr 
D) never identical 
E) none of the above 
A) always 140Xe and 94Sr 
B) always identical 
C) never 140Xe and 94Sr 
D) never identical 
E) none of the above

Question 20

For a controlled nuclear fusion reaction, one needs:

Accepted Answer

A) high number density n and high temperature T 
B) high number density n and low temperature T 
C) low number density n and high temperature T 
D) low number density n and low temperature T 
E) high number density n and temperature T = 0 K 
A) high number density n and high temperature T 
B) high number density n and low temperature T 
C) low number density n and high temperature T 
D) low number density n and low temperature T 
E) high number density n and temperature T = 0 K

Exam 42: Energy From the Nucleus

The first step of the proton-proton cycle is:

Separation of the isotopes of uranium requires a physical, rather than chemical, method because:

In the uranium disintegration series:

Tokamaks confine deuteron plasmas using:

Consider all possible fission events.Which of the following statements is true?

The energy released in a complete proton-proton cycle is about:

The overall proton-proton cycle is equivalent to:

Nuclear fusion in stars produces all the chemical elements with mass numbers less than:

Which one of the following represents a fission reaction that can be activated by slow neutrons?

Two billion years ago, a natural nuclear reactor formed in a uranium deposit in Africa.Why is it not possible for such a natural reactor to form somewhere on Earth today?

Lawson's number is 1020 s.m-3.If the density of deuteron nuclei is 2 * 1021 m-3 what should the confinement time be to achieve sustained fusion?

For purposes of a practical (energy producing)reaction one wants a disintegration energy Q that is:

In a subcritical nuclear reactor:

The energy supplied by a thermal neutron in a fission event is essentially its:

A nuclear reactor is operating at a certain power level, with its multiplication factor adjusted to unity.The control rods are now used to reduce the power output to one-half its former value.After the reduction in power the multiplication factor is maintained at:

The table lists properties of several heavy nuclei when they are struck by thermal neutrons; En is the excitation energy and Eb is the energy barrier.Which quantity, or combination of quantities, represents the energy put into the oscillation of the resulting compound nucleus?

Most of the energy produced by the Sun is due to:

235U is readily made fissionable by a thermal neutron but 238U is not because:

When 236U fissions the fragments are:

For a controlled nuclear fusion reaction, one needs:

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Lawson's number is 10²⁰ s.m^-3.If the density of deuteron nuclei is 2 * 10²¹ m^-3 what should the confinement time be to achieve sustained fusion?

The table lists properties of several heavy nuclei when they are struck by thermal neutrons; E_n is the excitation energy and E_b is the energy barrier.Which quantity, or combination of quantities, represents the energy put into the oscillation of the resulting compound nucleus?

²³⁵U is readily made fissionable by a thermal neutron but ²³⁸U is not because:

When ²³⁶U fissions the fragments are: